For years, lighting systems, such as ceiling mounted lighting fixtures or luminaires, have made use of fluorescent lamps and/or incandescent lamps. In addition to the lamps, lighting systems typically include an assembly of components, such as ballasts and reflectors. Luminaires that incorporate fluorescent lamps are the most commonly used commercial light sources due to their relatively high efficiency, diffuse light distribution characteristics, and long operating life. Luminaires that incorporate light emitting diodes are emerging as an attractive alternative to fluorescent lamp luminaires, providing marked improvements in efficiency and operating life.
Over the lifetime of a lighting system, for example, a commercial lighting system, the expenditures associated with operating and maintaining the system can be significant. As lighting fixtures age and deteriorate, the light-emitting ability degrades and the light output per unit of consumed electrical energy is significantly reduced. Modern ballasts, lamps and reflectors are available that can significantly enhance the light-emitting ability of the lighting system and also significantly enhance the energy efficiency by reducing the power consumption. As a result, the light output could be increased, while simultaneously reducing the associated energy costs. In many applications, long operating life, which reduces the burden of maintaining or replacing light fixtures, is seen as an important characteristic.